8-7
Fault
display
Probable cause and remedyFault name and meaning
ce
Communications time-over
(CE)
Normal RS-422/485
communications were not
established within 2 s. The
Inverter will detect this error if
n151 for RS-422/485
communications time over
detection selection is set to 0,
1, or 2.
• A short-circuit, ground fault, or disconnection has occurred
on the communications line.
→ Check and correct the line.
• The termination resistance setting is incorrect.
→ In the case of RS-422 communications, set pin 1 of SW2
of all Inverters to ON. In the case of RS-485
communications, set pin 1 of SW2 of only the Inverter
located at each end of the network to ON.
• Noise influence.
→ Do not wire the communications line along with power
lines in the same conduit.
→ Use the twisted-pair shielded wire for the
communications line, and ground it at the Master.
• Master’s program error.
→ Check and correct the program so that communications
will be performed more than once every 2-s period.
• Communications circuit damage.
→ If the same error is detected as a result of a
self-diagnostic test, change the Inverter.
Emergency stop (STP)
An emergency stop alarm is
input to a multi-function input.
(A multi-function input from 1
to 7 that was set to 19 or 21
has operated.)
• An emergency stop alarm is input.
→ Remove the cause of the fault.
• The sequence is incorrect.
→ Check and change the external fault input sequence
including the input timing and NO or NC contact.
FbL Feedback loss fault (FbL)
A feedback input was
interrupted during PID control
execution. (This fault is
detected when an input level
below the feedback loss
detection level set in n137
persists for longer than the
feedback loss detection time
set in n138.)
• Feedback wiring error.
→ Check for and correct any cable disconnection or faulty
wiring.
• Feedback sensor error
→ Check sensor status and replace any defective sensors.
• PID target value input error or feedback loss detection set-
ting error
→ Correct the target value input so that it is outside of the
feedback loss detection range. Correct the feedback loss
detection parameter settings (n137, n138).
• Feedback input circuit error
→ Replace the Inverter.
Maintenance Operations Chapter 8
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